Abstract
Leg-weakness was observed in a field flock of 82-day-old chickens, and a mesogenic Newcastle disease (ND) virus (TY-1 strain) was isolated from the brain of one affected chicken which revealed non-purulent encephalomyelitis characterized by necrosis of motor never cells in the brain and spinal cord. Clinical signs and lesions were reproduced in 6-month-old specific-pathogen-free chickens by an experimental infection with the TY-1 strain. These results indicate the existence of ND virus infection, which induces leg-weakness and obvious pathological changes in the central nervous system in the field.
